In photographic systems, a camera user captures the scene on a photosensitive film strip that is subsequently processed to create a stable record of the image, a "negative". This negative is then exposed in a photographic printing process onto a positive print paper to produce a positive image for normal, direct viewing. The quality of the resultant print depends on many variables involved in this technology; namely, light density and hue of the image, sensitivity of the emulsions and user preferences in color balance and density characteristics. Typically, these variables are dealt with in the printing stage by selectively controlling the duration of exposure for each of a plurality of colors of the light exposing the print paper. These controls may be inputted manually by the operator of photographic printer or they may be determined automatically using specially designed computer algorithms for the purpose.
Testing has shown that when a series of scenes are shown to a variety of viewers, the viewers express different preferences on color balance and exposure characteristics of the print. Some individuals prefer a color mix that is biased more toward the longer wave lengths in the red spectral wavelength region to produce a "warmer" image. Others may prefer a color bias toward shorter wavelengths in the blue spectral region. Normally, however, photographic printing processes, including the associated color balance control algorithms, when used, are set to generate prints that are based on a derived average preference of a wide variety of users.
It would be of benefit to camera users if their personal preferences as to color balance characteristics in reproduced image characteristics could be determined individually and the preference applied to the printing process to control the exposure of the prints.